Heating system



Oct. 23, 1945. c. w. GRAVES HEATING SYSTEM Filed Jan. 27, 1943 F M n P Vt W 1 11f q 1 4 /a /9 N m T 2 1J g I I N VEN TOR.

CHARLES \MBRAvEs,

Patented Oct. 23, 1945 UNITED STATES PATENT OFFICE 2,387,576 HEATINGSYSTEM Charles W. Graves, Arlington, Mass. Application January 27, 1943,Serial No. 473,720 g p c ZClaims. (Cl. 237-9) IThis invention relates tosteam heating systems of that class wherein heat is suppliedperiodically, or in cycles, to the radiators thereof under control of aroom thermostat, mechanically operated dampers or the like.

In systems of the class referred to ithas heretofore been commonpractice to equip each radiator with a thermostatic air vent valve ofthat type which permits the escape of relatively cool or cold air fromthe radiators as steam pressure is built up within the same, but whichcloses automatically when heated by the steam that is delivered-to theradiators.

It is also true of such systems that during periods of idleness of thesteam generator the temperature and pressure of the steam within eachradiator would at times fall suiilclently low to cause the radiator airvent valve to open and admit relatively cold air to the radiator torecharge the system with air at atmospheric pressure before thecommencement of the next heating cycle. This admission of cold air tothe radiator at such times was objectionable, mainly for the reason thatit reduced the temperature of the radiator and its contents at theexpense of heat units.

My invention has for its principal object to obviate the objectionablefeature just referred to and to provide an improved heating system ofthe class described so constructed and organized that when, duringoperation of the system, the pressure therein falls to slightly belowatmospheric pressure during a period of rest of the steam generator,then pre-heated air at atmos pheric pressure will be deliveredautomatically" into the system as required to maintain the pressuretherein approximately at atmospheric pressure so that no air is takeninto' the system through the radiator vent valves, said delivery ofpre-heated air being effected independently of the room thermostat orother heater-controlling means.

Other features of the invention are hereinafter pointed out.

In the accompanying drawing:

Figure 1 is a view, more or less diagrammatic, showing a heating systemconstructed and operating in accordance with this invention.

Figure 2 is an elevation, partly in section, of one of the air ventvalves hereinafter referred to. V

Figure 3 is an elevation, partly in section, of one of the radiatorvacuum air vent valves hereinatter referred to.

Figure 4 is a section on line 4-4-0! Fig. 1. I

The steam heating system illustrated :in"Fig,Z1 of the drawingcomprisesa steam generator l0 provided at its base with a. burner ll equippedwith .a control box. I! connected by a circuit l3 with a room thermostatI4 located withinone of the spaces or'rooms to \be heated. When circuitI3 is closed by thei'mostat H the .burner H is in operation and whenopened atthe thermostat the burner is out of operation.

Generator I0 is made with a boiler l5 within which water is maintainedat a predetermined level so as to provide a steam space It zatxthe topthereof. This steam space is connectedby risers ll withfthe radiators l8located within the spaces or rooms to be heated, the thermostat l4 beingarrangedwithin one of the latter. Adjacent to its radiator each riser I1is provided, as usual, with a shut-off valve I9 which is open while theradiator is in use.

Each radiator i8 is equipped with a vacuum air outlet valve 20 (Figs. 1and 3) which is preferably of a well known type that is inycommon use atthe present time. A valve of the kind referred to is also illustrated inFig. 3 of U. s. patent to Ferguson, et al., No. 2,06 2,565 datedDecember 1, 1936. v a e This type of valve comprises a base a to whichis secured a casing 22 by means of a coupling ring 0. An eilteriorlythreaded nipple d provided on base a is screwed into a tapped holeprovided in its radiator and loosely confined within said nipple is oneend of a syphon tube e which returns condensate to the radiator. At thetop of casing b is provided an outlet port ,1 formed with a valve seat'at its inner end. Adjustably mounted within the base a, and extendingbelow the same, is a tubular stem g which supports ajpressure-operatedbellows h disposed within casing b. This bellows abuts and supports athermostatic float 7' provided at its top with a valve stem kco-operating with the inner seat end of outlet port I. The inner end oftubular stem 9 communicates with .the interior of bellows .h while itsouter end communicates with the outside atmosphere.

The float j is supported by stem g and bellows h and usually has a smallquantity of 'vola tile liquid contained within. Thus when the float iscold thebottom thereof is concaved but when its temperature is raised bythepresence of steam within the valve said bottom is caused to assume aconvexshape due. to the expansion of thefluid within the float and thiselongation of the latter closes the valve k.

Because otthe fact that atmospheric pressure always exists within thebellows h the latter will be maintained in its normal unexpandedcondition so long as the pressure within casing b is at or aboveatmospheric pressure, but when, during operation of the system, thepressure within said casing falls below atmospheric pressure then thebellows tends to expand and will act through float 9' to maintain valvek in its closed position. In other Words the radiator valve 20 is Openwhen the system is first started thereby to permit air to vent from thesystem as the pressure and temperature within the latter builds up andwhen this takes place heat is transmitted from theradiator to thethermostatic element 7'. Fig. 3, which then operates to close valve 1c.Thereafter, during the operation of th system the valve 2|] remainsclosed and no air is permitted to enter at said valve when a vacuumdevelops within the system for reasons that-will appear later.

Thus, valve 20 is open only while the system is being started up andthen only until the steam reaches and heats its thermostatic floatwhereupon valve 2|) is automatically closed by expan- 'sion of thefloat. Thereafter, so long as the system is in operation and regardlessof pressure variation therein, the valve 20 will remain closed as willbe made clear later. I

' The top of the boiler I5 is made with a threaded aperture into whichis tightly screwed the lower exteriorly threaded end of an upwardlyextending metal pipe 2| Whose upper end is'closed by a cap 22. This pipe2|, in the illustrated example, is a one-inch iron pipe about six feetlong and it is maintained heated, particularly the lower end portionthereof, to a substantial degree by heat transmitted to it from the topof the boiler l5, so that it serves as presently to be described notonly as an air reservoir but also as an air heating retort.

At about eighteen inches above the top of generator ID the pipe retort2| is provided with a plurality of inwardly-opening thermostatic airinlet valve units 23 (Figs. 1, 2 and 4) which may each be constructed asshown in Fig. 2.

' Each air inlet valve .unit 23. comprises a base a into the top ofwhich is telescopically fitted and secured the lower end of a sheetmetal casing b. At one side thereof the base a is made with anexteriorly threaded nipple d screwed into a tapped hole provided in pipe2|. Nipple d is tubular and its inner end communicates with theinteriors of base a and easing b. Within this nipple is loosely confinedone end of a small syphon tube e for returning condensate ,topipe2l.

the seat at the inner end of port f. Air valves 23 of the type shown inFig. 2 of the drawing are old and well known.

Since the capacity of the inlet port I of each valve 23 is small I havefound it convenient and desirable, when using the standard make, to employ a plurality of these valves as shown in Figs. 1 and 4, in order toafford ample inlet capacity.

During each period of idleness of burner and cools the valves 23 whichthereupon open and the temperature and pressure of the steam within thesystem, including pipe 2|, teadily decreases and if and when thepressure passes slightly below the outside atmospheric pressure, thenthe accompanying proportionate reduction in the temperature of the topof boiler l5, pipe 2| and the valves 23, causes the latter to open andadmit air to the lower hot vertical section of pipe 2| by which it isheated as it passes through the same into the steam space of boiler l5.

Thi breaks the vacuum and immediately restores the pressure within theboiler to atmospheric, the pointer 3| of a steam pressure gauge 30 beingreturned from a negative position to its neutral position at zero on thegauge dial. Continued idleness of burner results in the pressurewithinthe system again falling to slightly belowatmospheric and this isaccompanied by the automatic-delivery of more pre-heated air into theboiler through valves 23 and pipe 2|, thereby again restoring pointer 3|to zero posi tion from a negative pressure-indicating position intowhich it is moved each time the pressure falls slightly belowatmospheric.

Valves 23 are normally closed and remain so until the pressure withinthe boiler falls below atmospheric whereupon the relatively cool air inthe upper part of pipe 2| expands downwardly admit air to the boilerwhich destroys the vacuum. The air thus admitted is preheated as itpasses through the lower hottest portion of the pipe 2 I.

In this way pre-heated air will be intermittently delivered into boilerl5, and pointer 3| will continue to be slightly vibrated between zero psition and a negative pressure-indicating position, so long as theburner remains idle.

During these air replenishing operations no cold air will enter theradiators l8 through the valves 20 for the reason that the latter areretained in their closed condition automatically by their bellows h eachtime the pressure falls below atmospheric.

When the burner H is again started by the room thermostat and thetemperature of pipe 2| and vent valves 23 i raised, the latter are againclosed and maintained so through expansion of their floats 7". Thiscondition continues to exist until the burner is again stopped and thepressure within the system again falls to slightly be low atmospheric orzero, whereupon the above described air replenishing action is repeated.

From the above description it will be observed that the radiator valves20 are thermostatically closed when the system isfirst started up andthat they are, maintained closed during the air replenishing period.Also that the valves 23 are primarily temperature-controlled althoughtheir opening movements are assisted by outside air pressure when thepressure within the system falls to just below atmospheric.

The heated pipe 2| serves as a reservoir holding a volume of heated airsome of which moves into the boiler I5 owing to expansion thereof as thepressure within the system declines during the first part of each periodof rest of the burner and before the valves '23 open, while the hottestportion of pipe 2| that is between the vent valves 22 and the boilerserves as a retort-conduit to pro-heat the air' that is admitted throughsaid valves 33 after said valves open.

wer

The cost of operating the above described system is greatly reduced fromthat entailed m op erating the system with the pipe retort 2|eliminated. One system operated by me and constructed as above describedshowed an operating cost of one and nine-tenths cents per hour while thesame system without the pipe retort and constructed as heretofore showedan operating cost of three and one-half cents per hour.

While I have herein shown a room thermostat II as automaticallycontrolling the generation of steam by boiler l so as to supply heatperiodically to the radiators, it is to be understood that any othersuitable means such, for example, as mechanically operated dampers, maybe employed in lieu thereof to serve this purpose, said other means, ofcourse, being appropriate to the type oi heater employed.

What I claim is:

1. In a steam heating system of the character described, the combinationwith a radiator equipped with a normally closed thermostatic air outletvalve, a steam generator including heating means, a room thermostat forautomatically controlling the operation of said heating means to supplysteam periodically to said radiator, and a riser through which steam isdelivered to said radiator from said generator, of a dead end reservoirhaving an outlet communicating with the steam space of said generator,said air reservoir being directly heated by the boiler of said generatorand also having an air inlet communicating with the outside atmosphere,and a valve controlling said air inlet and itself controlled by thetemperature of said reservoir and its contents so that immediately upona fall of the pressure within the system to a predetermined pointslightly dlfie e29 below atmospheric pressure said inlet-controllingvalve automatically opens to admit air to the system to break the vacuumtherein and prevent opening of said radiator outlet valve so that thelatter is maintained continuously closed during normal operation of thesystem.

2. In a steam heating system of the character described, the combinationwith a radiator equipped with a normally closed thermostatic outletvalve, a steam generator including heating means, mechanism forautomatically controlling and operating said heating means to supplysteam periodically to said radiator, and a riser through which steam isdelivered to said radiator from said generator, of an air-heatingreservoir consisting of a dead end length of metal pipe whereof one endis connected with, and communicates with the interior of, the upperportion of the boiler of said generator and whereof the opposite end ispermanently closed, said pipe being provided intermediate its ends andat a redetermined distance away from said generator with an inlet, and anormally closed thermostatic valve controlling said inlet so as to openthe latter for the admission of air to said pipe indep ently of saidradiator valve and said mechanism whenever the pressure within said pipefalls to a predetermined'point slightly below atmospheric pressurethereby to supply preheated air to said boiler to break the vacuumwithin the system and prevent entrance of air through said radia toroutlet valve.

- CHARLES W. GRAVES.

